The invention relates to a magnet supporting frame for a magnetically levitated vehicle. The magnets are electromagnets and their magnetic force is controlled by controlling the electrical energization of the magnet coils. The vehicle travels on a rail structure and the magnets are movably arranged in a frame secured to the vehicle so that the magnets are arranged in rows symmetrically to a plane extending vertically, longitudinally and centrally through the rail structure and hence also through the vehicle. The magnets are movable in the direction in which the magnetic forces are effective.
The magnets comprise levitation magnets and guide magnets. The electromagnetic attraction forces of these magnets are used to levitate and guide the vehicle whereby the rail structure operates as a back flow member to close the magnetic circuits. In order to keep the electrical input power within economically feasible limits, it is necessary to maintain suitable levitation and guide gaps between the magnets carried by the vehicle and the stationary rail structure. The gap width should be as small as possible preferably in the range of 5 to 15 millimeters. Maintaining such gap width for the desired levitational freedom involves two separate approaches. One approach relates to the closed loop or feedback control of the gap width. The other approach relates to the structural arrangement of the magnets. Both approaches must take into account criteria determined for a comfortable travel. The invention is directed to the structural arrangement of the magnets.
It is known in the art to support the magnets by means of springs for decoupling the electromagnets from the vehicle or from the frame carrying these magnets, in a vibratory sense. In other words, vibrations of the magnets must not affect the vehicle. Where a relatively large number of individual magnets are arranged in a row extending in the longitudinal direction of the vehicle, it is known to support these magnets individually by respective spring suspension means. Such individual spring suspension means have the drawback that any magnet may be individually subject to excursions to such an extent that the magnet contacts a rail, unless additional means are provided for individually guiding the movements of the magnets.
German Patent Publication (DE-OS) 2,633,647 discloses an effort for controlling such magnet excursions. Magnet tie down spring means are arranged so that the respective magnet is fettered to such an extent that the stabilizing moments resulting from an excursion, are larger than the moments which cause the magnet excursions in the first place. These tie down spring means also must satisfy predetermined stability criteria. However, such prior art tie down spring means cannot avoid that the respective magnet may take up a slanted position relative to a rail of the rail structure, even if the magnet is in a stable position relative to its frame, that is even when the magnet is not subject to an excursion. Such slanted magnet position relative to a rail may be due to positional faults in the rail structure. Under these circumstances there is a real danger that a magnet may impact on the rail becuase the magnetic forces of the electro-magnet are increasing as the gap or spacing between the magnet and the rail decreases. Thus, it has been preferred heretofore to use, in addition to the individual tie down spring means, a mechanical parallel guide for guiding the magnet relative to its frame.
However, it has been found that the gap width reduction and thus the reduction in the so-called levitational freedom which becomes posible due to the spring support means for the individual magnets on the one hand, becomes practically self defeating on the other hand due to unavoidable installation tolerances and deformations of the parallel or enforced guide means and of the magnet support frame as well as of the electromagnet itself. Stated differently, these factors make it practically impossible to maintain the desired gap width reduction which is intended to be achieved by the spring support means for the individual magnets especially if it is intended to normally avoid almost any contact between the magnets and the rail structure.
Further, it is inherent in the concept of individual spring supports for each magnet that a support base is required for the stabilization of each magnet. Such support base must be provided as a relatively stiff frame or chassis so that the spring means may become effective at all as a stabilizer or as an additional mechanical enforced guiding means. Consequently, and if one wants to minimize the structural weight of the magnet support frame, spring support means for each individual magnet should be avoided.
Thus, German Patent Publication (DE-OS) No. 2,837,191 does not solve the problem of adapting the position of the electromagnets to the rail course by arranging the electromagnets movable in the direction of the effect of the magnetic force on the support frame. Rather, this publication discloses a ligher, twistable construction of the magnet support frame. However, the frame according to this reference still has a larger stiffness against bending loads. The individual girders of the known frame are stiff against bending in order to be able to hold the respective electromagnet in a stable position, in other words to prevent it from performing angular movements in the pitching direction. Stated differently, the frame of DE-OS No. 2,837,191 permits, due to its twisting a position adaptation of the electromagnet to the rail course and the bending stiffness of the frame counteracts any destabilizing pitching movements of the magnet. Of course, such bending stiffness requires a substantial material investment, for example, in the form of profiled or sectional frame girders. Thus, the known frame does not constitute an optimal solution of the problem of minimizing the structural weight of the frame.